Spring-Mybatis读写分离笔记整理

public class ReadWriteDataSource extends AbstractRoutingDataSource {
     
    @Nullable
    @Override
    protected Object determineCurrentLookupKey() {
     
        return DsTypeHolder.get().getCode();
    }
}

@Intercepts({
     
   @Signature(type = Executor.class, method = "update",
           args = {
     MappedStatement.class, Object.class}),
   @Signature(type = Executor.class, method = "query",
           args = {
     MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}),
   @Signature(type = Executor.class, method = "query",
           args = {
     MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class})
})
public class DynamicDataSourceInterceptor implements Interceptor {
     
    private static final String REGEX = ".*insert\\u0020.*|.*delete\\u0020.*|.*update\\u0020.*" ;
    @Override
    public Object intercept(Invocation invocation) throws Throwable {
     
        boolean transactionActive = TransactionSynchronizationManager.isActualTransactionActive();
        DsType dsType = DsType.MASTER;
        if (!transactionActive){
     
            Object[] args = invocation.getArgs();
            MappedStatement ms = (MappedStatement) args[0] ;
            if (ms.getSqlCommandType().equals(SqlCommandType.SELECT)){
     
                // 如果selectKey为自增id查询主键，使用主库
                if (ms.getId().contains(SelectKeyGenerator.SELECT_KEY_SUFFIX)){
     
                    dsType = DsType.MASTER;
                }else {
     
                    BoundSql boundSql = ms.getSqlSource().getBoundSql(args[1]);
                    String sql = boundSql.getSql().toLowerCase(Locale.CHINA).replaceAll("[\\t\\n\\r]]", "");
                    // 如果是更新操作则切换到主库
                    if (sql.matches(REGEX)){
     
                        dsType = DsType.MASTER;
                    }else {
     
                        // 非更新操作则使用从库
                        dsType = DsType.SLAVE;
                    }
                }
            }
        }else {
     
            dsType = DsType.MASTER;
        }
        DsTypeHolder.set(dsType);
        return invocation.proceed();
    }
    @Override
    public Object plugin(Object target) {
     
        if (target instanceof Executor){
     
            return Plugin.wrap(target, this);
        }
        return target ;
    }
}

@Getter
public enum DsType {
     
    MASTER("master"),
    SLAVE("slave");

    private final String code ;

    DsType(String code){
     
        this.code = code ;
    }
}
public class DsTypeHolder {
     
    private static ThreadLocal<DsType> dsTypeThreadLocal = new ThreadLocal<>();

    public static void set(DsType dsType) {
     
        dsTypeThreadLocal.set(dsType);
    }

    public static DsType get() {
     
        if (dsTypeThreadLocal.get() == null){
     
            return DsType.MASTER ;
        }
        return dsTypeThreadLocal.get();
    }

    public static void clear() {
     
        dsTypeThreadLocal.remove();
    }
}

spring:
  application:
    name: hello-read-write-app
  jackson:
    time-zone: GMT+8
  datasource:
    master:
      driver-class-name: com.mysql.cj.jdbc.Driver
      jdbc-url: jdbc:mysql://127.0.0.1:3306/test
      username: root
      password: root
    slave:
      driver-class-name: com.mysql.cj.jdbc.Driver
      jdbc-url: jdbc:mysql://127.0.0.1:3306/test
      username: root
      password: root
logging:
  level:
    root: info
    com.yicj.study.rw.repository.mapper: debug
mybatis-plus:
  mapper-locations: classpath:/mapper/*Mapper.xml

@Configuration
public class DataSourceConfig {
     
    @Bean
    @ConfigurationProperties("spring.datasource.master")
    public DataSource masterDataSource() {
     
        return DataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties("spring.datasource.slave")
    public DataSource slaveDataSource() {
     
        return DataSourceBuilder.create().build();
    }

    @Bean
    public ReadWriteDataSource readWriteDataSource(
            @Qualifier("masterDataSource") DataSource masterDataSource,
            @Qualifier("slaveDataSource") DataSource slaveDataSource) {
     
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put(DsType.MASTER.getCode(), masterDataSource);
        targetDataSources.put(DsType.SLAVE.getCode(), slaveDataSource);
        //
        ReadWriteDataSource readWriteDataSource = new ReadWriteDataSource();
        readWriteDataSource.setDefaultTargetDataSource(masterDataSource);
        readWriteDataSource.setTargetDataSources(targetDataSources);
        return readWriteDataSource;
    }
}

@Configuration
public class MyBatisConfig {
     

    @Autowired
    private ReadWriteDataSource readWriteDataSource ;

    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
     
        MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
        sqlSessionFactory.setDataSource(readWriteDataSource);
        MybatisConfiguration configuration = new MybatisConfiguration();
        configuration.setJdbcTypeForNull(JdbcType.NULL);
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.setCacheEnabled(false);
        // 动态数据源拦截器配置
        configuration.addInterceptor(new DynamicDataSourceInterceptor());
        //如果配置多个插件,切记分页最后添加
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        configuration.addInterceptor(interceptor);
        sqlSessionFactory.setConfiguration(configuration);
        return sqlSessionFactory.getObject();
    }

    @Bean
    public PlatformTransactionManager platformTransactionManager() {
     
        return new DataSourceTransactionManager(readWriteDataSource);
    }
}